I hope you have model N905C?
I have similar symptoms only for N905(A).
On N905C I inserted the SD even Kobo Glo. Loading, but the screen is stretched

.
You can connect the USB-uart adapter (speed 11520) to
pads J5 in right-down corner PCB to terminal (putty) and observe whether the output is available?
If you see output like
File of internal uSD you can see under Linux.